Tray-like stackable container

ABSTRACT

Nestable tray-like containers are provided having an unbroken rim flange and rounded corners. The containers are erected from a flat blank to an angle of less than 90* to the horizontal plane, and the corner panels folded bellow-wise and joined together along a number of score lines.

United States Patent J ohansson [54] TRAY-LIKE STACKABLE CONTAINER [72] Inventor: Hans Ame Valendier J h Eslov, Sweden [73] Assignee: Mo och Domsjo ,Aktiebolag, Omskoldsvik, Sweden [22] Filed: July 6, 1971 [21] Appl. No.: 160,043

[30] 1 Foreign Application Priority Data July 6, 1970 Sweden ..9347/70 [52] US. Cl. ..229/31 R [51] Int. Cl. ..B65d 5/24 [58] Field of Search ..229/3.1, 3.5 MP, 31

[56] References Cited UNITED STATES PATENTS 2,071,892 2/1937 Moore ..229/31 R 2,407,118 9/1946 Waters .,...V....229/3. 5MF XV [451 Oct. 31, 1972 2,643,812 6/1953 Lange ..229/31 R 2,808,192 10/1957 Raisin ..229/3. 5 MF X 3,038,634 6/ 1962 Cheeley ..229/3.5 MF

9 3,536,248 10/1970 Odenhagen ..229/31 R 3,550,835 12/1970 Persson ..229/31 R 3,565,324 2/ 1971 Odenhagen 3....229/31 R FOREIGN PATENTS OR APPLICATIONS 303,453 8/1968 Sweden ..229/3 R Primary Examiner-Davis T. Moorhead Attorney-lanes & Chapman [57] ABSTRACT Nestable tray-like containers are provided having an unbroken rim flange and rounded comers. The containers are erected from a flat blank to an angle of less than 90 to the horizontal plane, and the comer panels folded bellow-wise and joined together along a number of score lines.

6Claims,4DrawingFigures PATENTEnnmm m2 3,701,467

sum 1 0r 2 Fig. I

PKTEN'TED mu 3 1 1922 SHEET 2 OF 2 TRAY-LIKE STACKABLE CONTAINER The present invention relates to a stackable, tray-like container with an unbroken rim flange and rounded corners. The invention is primarily concerned with containers which are liquidand/or airtight and to the rim flange portion of which a lid can be applied to seal the container. With such containers it is important that the upper surface of the flange portion is as flat as possible, to prevent leakage between the container and the lid. It is also desirable that the containers can be producedby erecting a pre-shaped blank. The problem with producing containers of the aforementioned type is that the corners of the container must be formed so that the aforementioned conditions are fulfilled whilst, at the same time, it must be possible to produce the product by means of a manufacturing method suitable for mass production with the use of inexpensive apparatus. If the top and/or the bottom portions of the comers are formed in right angles, by folding the comer panels along a number of score lines and recesses in the edge flange, the container is no longer capable of being nested in similar containers. Moreover, it should be noted that the more flaps which must be folded over each other in the corners the more complicated becomes the folding mechanism necessary to fold the flaps in this respect. Furthermore, if the container has right-angle corners there is the risk of a focused application of energy when heating the con: tainer in a micro-wave oven, i.e. heat impinges at the corners from two different directions and causes the contents of the container to burn. If there is an excess of score lines merging into the same corner, it is impossible to construct a tool for producing the container by machine, since the folds lie too close to one another. Each score line has a certain width, and consequently the more score lines which meet in a corner the more difficult it becomes to fold the corner mechanically. On the other hand, it is desired to have score lines terminating as close to the bottom as possible, otherwise the container is liable to become distorted when folding the same, resulting in faulty folds. If the rim flange is unbroken which is to advantage in itself, and is of uniform width throughout, step-like bulges are obtained along the normal edge subsequent to folding the container, which is a disadvantage. Moreover, if the thickness of the material is not taken into account when constructing a container, high stresses occur in the material subsequent to folding the container, when the flaps are folded over each other, which results in cracking of the basic material from which the container is made especially if the basic material iscardboard which in turn gives rise to non-desirable leaks. Finally, it must be ensured when constructing containers of the aforementioned type that there are no raw edges at the corners which are liable to come into contact with the contents and absorb the same by suction, when the contents are liquid, thereby discoloring the container and possibly causing the raw edge to disintegrate.

The present invention relates to a nestable, tray-like container having an unbroken rim flange and rounded cornersproduced by erecting a flat blank to an angle of less than 90 to the horizontal plane, and folding the corner panels bellow-wise and joining the corner panels along a number of score lines which do not present any of the aforementioned disadvantages. The container according to the present invention is mainly characterized in that the container blank is provided at each corner with three substantially triangular corner panels defined by four score lines and arranged on either side of a substantially rectangular central corner panel, and that the four score lines on either side of the central corner panel each converge towards the same point.

Moreover, the unbroken rim flange forming the outer portion of the corner panels is so formed that the outer portion of the rim flange for two of the comer panels is defined by a straight line and for the central comer panel and the comer panels adjacent thereto is defined by a curved line in a manner whereby the flange obtains a varying width and is narrowest at the point where the straight lines meet the curved lines.

The score lines of the rim flange in the substantially triangular comer panel are located at different distances from the converging point and the score line of the edge flange in the central corner panel is further removed from the converging point than the score line of the nearest located corner panel.

An embodiment of the invention is illustrated by way of example in the accompanying drawing.

FIG. 1 shows a portion of a flat blank intended for producing a rectangular container.

' FIG. 2 illustrates the folding sequence of a portion of the wall sections which form a corner of the container.

FIG. 3 illustrates the erected corner in perspective.

FIG. 4 is a section through a corner taken along the line IV IV in FIG. 2.

When producing the illustrated container, which is intended to contain foodstuffs or the like which must be enclosed in a liquidtight container, a pre-formed and optionally embossed blank 1 is used in accordance with the invention. The blank 1 comprises cardboard material which is coated on both sides with a layer of heat-scalable material, preferably polypropylene or polyethylene. The plastic layer applied to thatportion of the blank which is to form the interior of the container is suitably considerably thicker than the layer applied to the outside of the container, for example twice as thick.

The blank partially shown in FIG. 1 includes a bottom surface 2, which merges via score lines 3 and 4 into the corresponding side wall portions 5 and 6. The side wall portion 5 and 6 merge through score lines 7, 7' with flange portion 8, 8. The bottom surface 2 is connected via an arcuate score line 9 with a corner segment (a center panel) 10 which is connected via score lines 11, 11' with first junction segments 12, 12' each of which, via score lines l4, 14 extending from points 13, 13', from which the score lines 11, 11' also extend, merge with second junction segments l5, 15', which via score lines 16, 16, also extending from the points 13, 13, merge with third junction segments 17, 17' which are connected via score lines 18, 18', also extending from the points 13, 13', with the adjacent sides 5 and 6 respectively. Although the lines 11, 11'; 14, l4; 16, 16'; and 18, 18' need not extend from the points 13, 13, they should be such that their imaginary extensionspass through said points. As will be evident from FIG. 1, the two halves of the corner construction are allochiral in relation to each other.

The corner segment is connected through an arcuate score line 19 with a flange portion 20 of arcuate outer contours. In a corresponding manner, the segments 12, 12 are connected through score lines 21, 21 with flange segments 22, 22' and the segments 15, are connected through score lines 23, 23' with flange segments 24, 24. Finally, the segments 17, 17' are connected through score lines 25, 25' with flange portions 26, 26'. As shown in FIG. 1 the score lines 19, 21, 21', 23, 23' and 25, 25' are spaced at different distances from the common points 13, 13 and the reason for this is that the flange segments, when erecting the container, shall lie in substantially one and the same plane. For the same purpose there are arranged in the flange segments 22, 22 small recesses 27, 27 the purpose of which is to thin the material at those positions where three layers of material are laid on top of each other. The outer portions 28, 28' of the score lines 11, 11 extend in at a slight angle to the remainder of the score lines for a purpose to be hereinafter explained.

In accordance with the invention, the container is produced by folding the flat blank illustrated in FIG. 1 in a special tool, the junction segments being folded bellow-wise over each other and sealed together in conjunction herewith. As will be evident from FIGS. 2 and 4, the segment 15 is folded outwards in a manner whereby the outer side of the segment 15 abuts the outer side of the segment 17. In this way, the flange portion 26 of the segment 17 will also abut the flange portion 24 of the segment 15. In connection with this folding step, the inside of the segment 15 is moved into abutment with the inside of of segment 12, and at the same time, the flange portions 24 and 22 of the segments come into contact with each other. The flange portions are suitably also folded during this folding step. In connection with the folding step, or immediately prior thereto, heat is applied to the segments 12, 15 and 17 and their flange portions by means, for example, of thermostat-controlled heated strips. In this way, the corresponding heat scalable layers of the material are melted so that a durable joint is obtained between the segments. In this way, the outer surface of the segments 17 is welded firmly to the outer surface of the segment 15 and the inner surface of the latter segment is welded firmly to the inner surface of the segment 12. A corresponding seal is, of course, also efi'ected between corresponding portions of the flange segments. As previously mentioned, the recess 27 causes the material at the portion of the flange portion where three layers of material are in superposed relationship to be thinner than the remainder of the material. Owing to the small angular deviation of the portion 28 of the score line 1 1, the flange portion of the corner element 10 can be lifted up, by means of a shoulder or like arranged in the tool, by an amount which causes the flange portion 20 to be flush with the remaining flange portions of the corner. As previously mentioned, the score lines 9 and 19 are arcuate in shape, which in addition to the rounded corner also causes the flange portion to tend to fold outwardly without wrinkling.

I The corresponding portions in the other half of the corner are folded and treated in a corresponding manner, so that the resulting corner obtains the appe a rance illustrated in principlejn FIG.

avmg regard to the foregoing disc osure, the following is claimed as the inventive and patentable embodiments thereof:

1. A stackable, tray-like container having an unbroken rim flange and rounded corners produced by erecting a flat blank to an angle less than 90 to the horizontal plane and by bellow-wise folding and joining the comer panels along a number of score lines, characterized in that the container blank is provided in each corner with three substantially triangular comer panels defined by four score lines, said corner panels being arranged on either side of a substantially rectangular central corner panel, that the four score lines on either side of the central corner panel each converge towards the same point, that the unbroken corner flange forming the outer portion of the comer panel is so constructed that the outer portion of the comer flange for two of the corner panels is defined by straight lines and for the central corner panel and the nearest adjacent corner panel is defined by an arcuate line in a manner so that the edge flange obtains a varying width and is narrowest at the point where the straight lines meet the arcuate line, that the score lines of the edge flange in the substantially triangular corner panels are located at different distances from the converging point, and that the score line of the edge flange in the central corner panel is farther removed from the converging point than the score line of the closest corner panel.

2. A container according to claim 1, characterized in that the score line of the central comer panel is arcuate at the bottom surface.

3. A container according to claim 1, characterized in that the distance between the score lines defining the rim flange of the substantially triangular comer panels is substantially equal to the thickness of the packaging material and that the distance between the score lines defining the edge flange of the central corner panel and the rim flange and the score lines defining the rim flange of the closest comer panel is substantially equal to twice the thickness of the container.

4. A container according to claim 1, characterized in that the outer portion of the score lines forming the central comer panel deviate slightly from the remainder of said score lines.

5. A container according to claim 1, characterized in that at least one of the score lines directed towards the converging point is only scored along a portion of the full distance from the rim flange to the converging point.

6. A container according to claim 1, characterized in that the container material is cardboard which is coated on both sides with a layer of heat-sealable plastic material and that the thickness of the plastic material is greater on the inside of the container than on the outside thereof. 

1. A stackable, tray-like container having an unbroken rim flange and rounded corners produced by erecting a flat blank to an angle less than 90* to the horizontal plane and by bellow-wise folding and joining the corner panels along a number of score lines, characterized in that the container blank is provided in each corner with three substantially triangular corner panels defined by four score lines, said corner panels being arranged on either side of a substantially rectangular central corner panel, that the four score lines on either side of the central corner panel each converge towards the same point, that the unbroken corner flange forming the outer portion of the corner panel is so constructed that the outer portion of the corner flange for two of the corner panels is defined by straight lines and for the central corner panel and the nearest adjacent corner panel is defined by an arcuate line in a manner so that the edge flange obtains a varying width and is narrowest at the point where the straight lines meet the arcuate line, that the score lines of the edge flange in the substantially triangular corner panels are located at different distances from the converging point, and that the score line of the edge flange in the central corner panel is farther removed from the converging point than the score line of the closest corner panel.
 2. A container according to claim 1, characterized in that the score line of the central corner panel is arcuate at the bottom surface.
 3. A container according to claim 1, characterized in that the distance between the score lines defining the rim flange of the substantially triangular corner panels is substantially equal to the thickness of the packaging material and that the distance between the score lines defining the edge flange of the central corner panel and the rim flange and the score lines defining the rim flange of the closest corner panel is substantially equal to twice the thickness of the container.
 4. A container according to claim 1, characterized in that the outer portion of the score lines forming the central corner panel deviate slightly from the remainder of said score lines.
 5. A container according to claim 1, characterized in that at least one of the score lines directed towards the converging point is only scored along a portion of the full distance from the rim flange to the converging point.
 6. A container according to claim 1, characterized in that the container material is cardboard which is coated on both sides with a layer of heat-sealable plastic material and that the thickness of the plastic material is greater on the inside of the container than on the outside thereof. 